CHICAGO, Feb 7 (Reuters) - Three men accused of plotting to attack high-profile targets during a 2012 NATO summit in Chicago were convicted on Friday on mob action and arson charges, but they were acquitted on terrorism-related charges in a setback for prosecutors.

The men, known as the "NATO 3," had faced seven charges each, including conspiracy to commit terrorism under a state anti-terrorism law adopted after the Sept. 11, 2001, attacks.

Brian Jacob Church, 22, and Brent Betterly, 25, both of Florida, and Jared Chase, 29, of New Hampshire, face four to 30 years in prison when they are sentenced on Feb. 28.

Defense attorneys called the jury verdict a big victory for their clients, who have been in prison since their arrests in May 2012, days before the start of the North Atlantic Treaty Organization meeting.

"This was a politically motivated, overcharged case to make an example to keep people off the streets during NATO," Sarah Gelsomino, an attorney for Church, told Reuters. She said he was relieved not to be branded a terrorist.

The three men looked solemn when the verdicts were read, and some of their supporters in the courtroom wept.

Defense attorneys had described the three as drunken braggarts who had been egged on by older undercover officers - "goofs" more interested in getting high than being violent.

The prosecution said the three were intent on mayhem, and had made Molotov cocktails with beer bottles and gasoline. Church had asked in a recording, "Are you ready to see a police officer on fire?"

Jurors, who began their deliberations on Thursday evening, found the men not guilty of the most severe charge - providing material support to commit terrorism - along with conspiracy to commit terrorism. The case marked the first time Illinois prosecutors had invoked the terrorism conspiracy charge.

Cook County State's Attorney Anita Alvarez defended her decision to bring the terrorism charges. She told reporters the arrests and prosecution protected the public.

"Do we have to wait for a Chicago police officer to be set on fire?" Alvarez asked reporters. "I don't think so."

Jurors declined to talk to reporters after the verdict.

The three were accused of planning attacks using fire bombs and other weapons, targeting police stations, President Barack Obama's re-election headquarters and Mayor Rahm Emanuel's house, along with other locations.

The summit attracted thousands of protesters, who were met by a strong police presence. Chicago had spent millions of dollars for security and other costs for the summit.

Chicago police, along with the FBI and the Secret Service, raided the Chicago apartment the three men used as a safe house and recovered pipe bomb instructions, an improvised mortar made from PVC piping, a crossbow, knives, throwing stars, a map of Chicago and four fire bombs. (Reporting by Mary Wisniewski; Writing by David Bailey; Editing by Leslie Adler, Grant McCool and Ken Wills)